Handles a run to line operation. Clients implementing a run to line action
can use this handler to carry out a run to line operation implemented with
a breakpoint. Handles the user preference to skip breakpoints while performing
a run to line operation, and cancelling the run to line operation if another
breakpoint is encountered before the operation is completed.

monitor - a progress monitor, or null if progress reporting and
cancellation are not desired. The monitor is only valid for the duration
of the invocation of this method. Callers may call IProgressMonitor.done()
after this method returns or throws an exception, but this is not strictly
required.